None.
Not Applicable.
The present invention relates generally to antifriction bearings and, more particularly, to fully self-aligning roller bearings which allow for simultaneous combination axial misalignment and axial displacement.
The typical antifriction bearing supports a shaft of one type or another in a housing, which surrounds the shaft, and likewise may take any of a variety of forms. The bearing, of course, enables the shaft to rotate in the housing or the housing to rotate around the shaft with minimum friction. Some antifriction bearings of current manufacture allow for misalignment or axial displacement of the rotating shaft relative to the housing, but not both. Axial misalignment occurs when the axis of the shaft is not parallel to the axis of the housing. Axial displacement occurs when the shaft moves generally parallel to the bearing axis relative to the housing or vice versa.
Some antifriction bearings currently available allow only for axial misalignment or axial displacement, but none of the current bearings are capable of offering the ability to dynamically compensate for significant axial misalignment and axial displacement simultaneously. As a result, when an antifriction bearing capable of compensating for axial misalignment is loaded with forces tending to cause axial displacement, components of the bearing are over-stressed with a resultant reduction in the life span of the bearing. Similarly, when a bearing capable of compensating axial displacement is loaded with forces tending to cause axial misalignment, the bearing components are again overloaded and the bearing life span is subsequently reduced.
The life of an antifriction bearing is also quite dependant on the amount of friction within the bearing components. Higher friction induces greater wear on each of the individual components of the bearing. Most of this bearing friction results from either excessive point loading on the bearing components or inadequate lubrication of the bearing components. Excessive point loading occurs when the rolling elements slip on the bearing raceways causing the rolling elements to skew. Although some bearing designs attempt to minimize this friction through various means of lubrication, current bearing designs tend to lack the ability to trap the lubricating fluids within the proper area of the bearing where the friction is most likely to occur.
The present invention overcomes these and other problems by providing an almost unlimited capacity to dynamically and simultaneously compensate for both axial misalignment and axial displacement. The design of the rollers allows for axial misalignment through the interaction of curved surfaces of the rollers with a spherical raceway on one of its races, and for axial displacement through the interaction of cylindrical surfaces on the rollers with a cylindrical raceway on the other race. Additionally, the design of the rollers allows for a quantity of lubricant to be maintained within the cavities between the rollers and the inner and outer raceway, and be distributed to the contact areas between the rollers and the inner and outer raceways to effectively lubricate the bearing.
This same roller design also provides for generally uniform distribution of the stresses within the bearing to provide for equal contact strength at both the inner and outer raceways. By equalizing the stresses and the strengths placed upon these raceways, the life of the bearing is significantly extended.
Part of this equalization is also attributable to the absence of ribs on the raceways to contain the rollers during bearing operation. Most bearings require annular ribbed surfaces integrated with the raceway designs to capture the rolling elements within the bearing. While these ribs succeed in retaining the rolling elements within the bearing, they also create significant wear within the bearing. During operation of such bearings, the rolling elements tend to rub against the ribs as the rolling elements attempt to equalize the internal forces of the bearing through dimensional displacement. This rubbing not only creates significant heat and causes wear to roller ends, it also causes the rollers to skew on the raceways. This significantly affects the bearing""s performance. The lack of these retaining ribs on the races of the present bearings eliminates this heat and wear within the bearing components and reduces the tendency of roller skewing.
To achieve all of the above delineated effects, a number of algorithms dictate the dimensional relationship between the internal components of the bearing. These algorithms identify the anticipated loads and displacements for calculation of the various radii and inter-dimensional relationships needed to sustain the advantages of the bearing.
This invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed.
Therefore, the present invention resides in a bearing having inner and outer races and rollers between the races. One of the races has a cylindrical raceway and the other a spherical raceway. The rollers have surfaces which conform to the raceways. The geometry of the rollers and raceways is such that the bearing accommodates axial misalignment of the races and also axial displacement of the races.
It is an object of the invention to provide a fully self-aligning roller bearing capable of providing an almost unlimited capacity for axial misalignment and for axial displacement.
It is another object of the invention to provide an antifriction bearing which allows for equal strength design of the rollers and the inner and outer raceways of the bearing.
It is also an object of the invention to provide an antifriction bearing which reduces the internal frictions of the bearing through a design of the rollers which tends to captivate and apply lubricants to contact surfaces within the bearing.
It is yet another object of the invention to provide a bearing design that inherently reduces the amount of heat generated during bearing operation, thereby extending the useful life of the bearing.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.